Blue Consecrated Sphinx This would be stopped by the fact that it cost except for the fact that every time I see anyone playing it, they're cheating it out
In the case of the former, its because the best choices vary not only by color identity, but often by specific deck building limitations: Seismic Assault and many other red effects want you to play an extra-high land count, while a black deck with reanimation and Tortured Existence obviously cares about discarding creatures
Moldering Karok Wins Out This deck, on the other hand, is a BO1 draft deck I 7-0d with on MTG Arena Premier Draft
TCGplayer also has a mobile app that makes uploading a collection easier, though its probably not the best for inventorying large amounts of bulk, since you need to individually scan cards
Yet its not gone for good: on a later turn, you can cast it again from exile, this time for its full cost